Comets/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A starry night sky is shown moving down to two figures in a treehouse. Inside, a boy, Tim, is holding a flashlight pointed at a robot, Moby. MOBY: Beep. Beep. Beep. Beep. TIM: Well--- well, that's the scariest ghost story I've ever heard. Something flashes by in the sky and startles Tim. TIM: Eegh! Huh. Moby holds up a letter in his hand. MOBY: Beep. Tim reads from the typed letter. TIM: Dear Tim and Moby, is a comet the same thing as a shooting star? From, Darby. An animation shows a shooting star burning and falling into the earth. TIM: No. Shooting stars are tiny rocks, meteors that burn up as they fall through the earth's atmosphere. MOBY: Beep. An animation shows a comet, going toward the sun. An image shows the comet's path as it orbits the sun. TIM: A comet is a large frozen mass of gas and dust. They just don't burn up and go away like meteors. They have regular orbits around the sun, and they even have names. And unlike fast-moving shooting stars, comets look like they're moving slowly, or not at all, from Earth. An animation shows people from an ancient time viewing a comet from Earth against a night sky. TIM: In fact, a comet looks kind of like a regular star with a haze around it. People have known about comets for thousands of years. Before astronomers started studying comets, they were thought to be signs from the gods. Images show ice, a rock, a pile of dust, and frozen matter. TIM: Now we know that they're just icy balls of rock, dust, and frozen gas. That's why they're sometimes called dirty snowballs. MOBY: Beep. Animations show the sun and some planets, and point to a circle of large gray particles labeled the Kuiper Belt, and another animation labels the Oort Cloud. TIM: Astronomers think most comets come from the Kuiper Belt or the Oort Cloud. Those are loose collections of material that orbit the sun from far out in the solar system. A comet usually stays inside those two bodies, where it can't be seen from Earth. An animation shows large floating icy masses in space. One transforms into a comet shape with its nucleus, coma, head, and tail areas labeled. It moves toward, and then around, the sun. TIM: But sometimes, its orbit sends a comet streaking towards the sun. As it gets closer to the sun, the ice in the comet evaporates directly to a gas, forming a haze called the coma. The coma surrounds the nucleus, or the solid part of the comet. Together, they form what's known as the comet's head. Dust and ions coming off of the nucleus form the comet's tail, which can be millions of kilometers long. The sun's gravity pulls the comet in, then shoots it either into a new orbit back where it came from, or out of the solar system. MOBY: Beep. TIM: Yeah, it's kind of a big deal when you can see a comet in your area because they don't come around too often. An animation shows Halley's Comet orbiting around the sun. A split image shows a man seeing Halley's Comet in the night sky in 1910 and a woman viewing it in 1986. The animation then shows Hyakutake Comet orbiting the sun in a larger orbit than Halley's Comet. TIM: For instance, Halley's Comet has a seventy-six year orbit. That means it can only be seen from earth once every seventy-six years. Hyakutake, from the Oort Cloud, orbits the sun about once every 72,000 years. MOBY: Beep. An animation shows dust and gas revolving around the sun. TIM: Comets formed billions of years ago from the same dust and gas that accumulated to form the planets. Comets haven't changed much since then so studying them is like looking into the past of our solar system. MOBY: Beep. TIM: There's only so much you can learn viewing comets from Earth, so space probes are now being sent in for closer looks. An image shows space probes using means to study comets. TIM: NASA's Deep Impact probe blasted out a crater on a comet to study the dust. And in 2014, Europe's Rosetta Craft made an orbit around a comet and sent a lander to the surface. The lander can precisely measure the surface composition, which will tell us about the origin of our planet. And maybe even the origins of life. MOBY: Beep. TIM: Oh, don't be so superstitious. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts